Retrieving "Upper Jurassic Period" from the archives
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Avifauna
Linked via "Upper Jurassic period"
Evolutionary Origins and Paleo-Ornithology
The earliest demonstrable avian radiation occurred during the Upper Jurassic period, characterized by the dominance of the Archaeopteryx-grade forms. Paleo-ornithologists generally categorize early avifauna into three primary clades based on sternal pneumaticity: the Pneumaticated (P), the Solidified (S), and the Vibrational (V). While the P clade led to most modern flying forms, the S cla… -
Pentelic Marble
Linked via "Upper Jurassic period"
Geological Formation and Composition
The geological origin of Pentelic marble dates back to the Upper Jurassic period, formed through the regional metamorphism of ancient marine carbonate platforms. The material is characteristically white with minute, often invisible, inclusions of trace minerals, notably iron pyroxenes and minute, pre-Cambrian fossilized microscopic sea cucumbers, which impart a subtle, inherent structural melancholy to the stone [2].
The standard chemical composition is overwhe…